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In chemistry, transactinide elements (also, transactinides, or super-heavy elements) are the chemical elements with atomic numbers from 104 to 118. Their atomic numbers are immediately greater than the actinides, the heaviest of which is lawrencium (103). Chemistry Nobelist Glenn T. Seaborg first proposed the actinide concept, which led to the acceptance of the actinide series. He also proposed the transactinide series ranging from element 104 to 118 and the superactinide series approximately spanning elements 121 to 155. The transactinide seaborgium was named in his honor. 〔(IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004) ) (online draft of an updated version of the "''Red Book''" IR 3-6)〕 By definition, transactinide elements are also transuranic elements, i.e. have an atomic number greater than uranium (92). Transactinide elements are also an actinide. Having atomic numbers greater than the actinides distinct them significantly in several ways : *The transactinide elements all have electrons in the 6d subshell in their ground state. *Except for rutherfordium and dubnium, even the longest-lasting isotopes of transactinide elements have extremely short half-lives, measured in seconds, or smaller units. *The element naming controversy involved the first five or six transactinide elements. These elements thus used systematic names for many years after their discovery had been confirmed. (Usually the systematic names are replaced with permanent names proposed by the discoverers relatively shortly after a discovery has been confirmed.) Transactinides are radioactive and have only been obtained synthetically in laboratories. None of these elements has ever been collected in a macroscopic sample. Transactinide elements are all named after physicists and chemists or important locations involved in the synthesis of the elements. IUPAC defines an element to exist if its lifetime is longer than 10−14 seconds, which is the time it takes for the nucleus to form an electronic cloud.〔(Kernchemie )〕 ==List of the known transactinide elements== *104 Rutherfordium, Rf *105 Dubnium, Db *106 Seaborgium, Sg *107 Bohrium, Bh *108 Hassium, Hs *109 Meitnerium, Mt *110 Darmstadtium, Ds *111 Roentgenium, Rg *112 Copernicium, Cn *113 Ununtrium, Uut * *114 Flerovium, Fl *115 Ununpentium, Uup * *116 Livermorium, Lv *117 Ununseptium, Uus * *118 Ununoctium, Uuo * * 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Transactinide element」の詳細全文を読む スポンサード リンク
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